Effects Of Calycosin Isoflavone Derivatives On Immune Function And Growth Performance Of Broilers

Immunopotentiators are a class of substances that are used alone or in combination with antigens to enhance the non-specific and specific immunity of animal bodies through different modes of action,such as enhancing macrophage activity,immunogenicity and stability of antigenic substances,and promoting antibody synthesis and secretion.There are many kinds of immune enhancers with different characteristics.Among them,traditional Chinese medicine immune enhancers have the functions of active stimulation,nutrition,regulation,antibacterial and antiviral.Calycosin is a flavonoid compound,mainly extracted from Astragalus,molecular formula is C₁₆H₁₂O₅.It has a variety of biological activities such as immune regulation,anti-inflammatory,antiviral,anti-tumor,and shows the characteristics of phytoestrogens.Calycosin is a promising natural medicine,but its research on enhancing immune function is not systematic enough,and its application in livestock and poultry has not been reported.The purpose of this study was to detect the effects of two new structural derivatives modified on the basis of plant monomer calycosin on immune function and growth performance of broilers.A total of 120 one-day-old broilers were randomly divided into 4 groups with 3 replicates per group and 10 broilers per replicate.Four groups were levamisole group（group A）,blank control group（group B）,DX073 group（group C）,DX075 group（group D）.The experiment lasted for 35 days.At the age of 7 days,0.3 ml drug was injected subcutaneously into the neck.Group A was injected with levamisole,group B was injected with normal saline,group C was injected with calycosin DX073 preparation with a concentration of 0.3 ml-2%,and group D was injected with calycosin DX075 preparation with a concentration of 0.3 ml-2%.At 7 days of age,the attenuated vaccine（Strain La Sota+Strain H120）was immunized,and the inactivated vaccine（Strain La Sota+Strain M14+Strain YBF003）was immunized at 8days of age.At the first,second,third and fourth weeks after injection,blood samples were collected from 5 chickens randomly selected from each group to detect serum avian influenza H9 and Newcastle disease antibody levels,peripheral blood T lymphocyte transformation rate,immunoglobulin G,interleukin-2,interleukin-4,interferon-γ,superoxide dismutase,malondialdehyde and growth performance;Three chickens were randomly selected from each group to detect blood routine at 1 and 3 weeks after injection.At 4 weeks after injection,the immune organ index was detected.the results are as follows:1.Antibody titer:There was no significant difference in antibody levels between the groups before and after the first week of injection.The level of avian influenza H9 antibody in the DX073 group was higher than that in the blank control group at the second and fourth weeks after injection.The antibody level of avian influenza H9 in the DX075 group was higher than that in the blank control group at the second,third and fourth weeks after injection,and the antibody titer was the highest at the fourth week,reaching 10.8 log₂.There was no significant difference in Newcastle disease antibody levels between the groups（P>0.05）.2.T lymphocyte transformation rate:The T lymphocyte transformation rate of DX073group and DX075 group was higher than that of blank control group at the first,second,third and fourth weeks after injection,and the T lymphocyte transformation rate of DX073 group was significantly higher than that of blank control group at the second and third weeks after injection（P<0.05）.At the fourth week after injection,the T lymphocyte transformation rate of DX075 group was significantly higher than that of blank control group and levamisole group（P<0.05）.3.Blood routine test:At the first week after injection,the contents of white blood cells,neutrophils,eosinophils,red blood cells,hemoglobin concentration and hematocrit in the DX073 group were higher than those in the blank control group.The content of neutrophils was significantly higher than that of blank control group and levamisole group（P<0.05）.At the third week after injection,the monocyte content in the DX073 group was higher than that in the blank control group.The content of monocytes and eosinophils in DX075 group was higher than that in blank control group,and the content of eosinophils in DX075 group was significantly higher than that in blank control group and levamisole group（P<0.05）.4.Immunoglobulin G and cytokine content:The content of Ig G,IL-2 and IL-4 in the DX073 group were significantly higher than those in the blank control group at the first and fourth weeks after injection（P<0.05）.The content of Ig G,IL-2,IL-4 and IFN-γin the DX075group were higher than those in the blank control group at the first,second,third and fourth weeks after injection.（1）Immunoglobulin G:The Ig G content in the DX075 group was significantly higher than that in the blank control group at the second and fourth weeks after injection（P<0.05）.（2）Interleukin-2:The content of IL-2 in DX075 group was significantly higher than that in blank control group（P<0.05）.The fourth week was significantly higher than the blank control group（P<0.01）.（3）Interleukin-4:The content of IL-4 in the DX075 group was significantly higher than that in the blank control group at the second and third weeks after injection（P<0.05）.The fourth week was significantly higher than the blank control group（P<0.01）.（4）Interferon-γ:The content of IFN-γin the DX073 group was higher than that in the blank control group at the first and fourth weeks after injection,and the content of IFN-γin the first week was significantly higher than that in the blank control group（P<0.05）.The content of IFN-γin DX075 group was significantly higher than that in blank control group at the first,second and fourth weeks after injection（P<0.05）.5.Antioxidant system related enzyme activity（1）Superoxide Dismutase:The content of SOD in DX073 group was significantly higher than that in blank control group at the second week after injection.（P<0.05）.（2）Malonaldehyde:The MDA content in the DX073 group was lower than that in the blank control group at the second and third weeks after injection,and the MDA content in the second week after injection was significantly lower than that in the blank control group and the levamisole group（P<0.05）.6.Growth performance and Immune organ index:From 21 to 35 days of age,the body weight of broilers in DX073 group and DX075 group was higher than that in blank control group.At 35 days of age,the average daily gain（ADG）of DX073 group and DX075 group was higher than that of blank control group.The feed conversion ratio（FCR）was significantly lower than that of the blank control group（P<0.05）.There was no significant difference in the index of thymus,spleen and bursa of Fabricius among the groups（P>0.05）.In summary,subcutaneous injection of 0.3 m L of two calycosin derivative preparations with a concentration of 2%can increase the peripheral blood T lymphocyte transformation rate of broilers to varying degrees,increase the serum Ig G,IL-2,IL-4 and IFN-γlevels of broilers,and significantly reduce the feed-to-weight ratio.